It will be months and years before Maryland utilities must meet some of the new standards meant to curb power outages, particularly those requiring the number and length of outages to decrease annually through 2015.

Yet many of the standards — which lawmakers required the state's Public Service Commission to set after widespread, extended outages from storms the past two years — went into effect before and just after a derecho storm June 29 took down trees and turned off the electricity for almost one million Marylanders.

No longer will utilities and the PSC, which is expected to continue setting the rules and enforcing them, be free to use subjective standards that did little more than direct utilities to avoid service interruptions and to restore service as soon as safely possible.

A number of the new standards took effect July 1.

There still is no set timeline for how quickly power must be restored when outages affect more than 400,000 or 40 percent of customers.

As of then, when storms or other major events cause outages to fewer customers, utilities are expected to restore service to at least 95 percent of their customers within 50 hours of when they knew, or should have known, that power was out.

And when outages occur during normal conditions, known as "blue sky days," utilities are expected to restore service to at least 92 percent of customers within eight hours.

Most of the regulations did not exist before, PSC spokeswoman Regina Davis said.

Pepco, the state's second-largest utility and the most frequent target of customer anger, and its sister utility Delmarva Power and Light, are the only utilities that will have to decrease both the length and frequency of outages this year to meet standards the PSC set for each utility, with improvements expected annually from 2012 through 2015.

"We're going to do it," said Bob Hainey, a spokesman for Pepco, which says customers served by upgraded power lines already have seen a 39 percent reduction in outages on "blue sky days."

Asked how the PSC will make sure it looks at utilities' performance data more critically than it did previously, agency spokeswoman Davis pointed to "objectively high standards," which replaced largely subjective ones, as the key.

"The Commission can and will enforce those standards across the state. If the companies comply, as we expect they will, reliability will improve and if they don't, we will take all appropriate steps," Davis said in an email.

The new regulations also require utilities to keep overhead lines clear of tree branches above and around conductors until trimming is done again in four or five years.

"The reality is we have already begun implementing programs ... [and] are going to be conducting additional tree trimming and pruning along overhead lines, especially close to substations" to cut the risk of large outages, said Rob Gould, a vice president at Baltimore Gas & Electric, the state's largest electricity provider, with more than 1.24 million customers in central Maryland.

BGE already has 62 percent of its roughly 25,000 miles of distribution lines buried underground.

However, the utility has ramped up trimming trees — which utilities point to as a major cause of outages in storms — fairly steadily, with spending on it increasing from $23.56 million in 2007 to $34.5 million in 2011.

Potomac Edison, which serves 250,000 customers in western and central Maryland, plans to spend an additional $1.2 million on tree trimming in Maryland in 2012, raising its total to $8.5 million, according to spokesman Todd Meyers.

"We already have reliability standards [we] have to meet in other states," said Scott Surgeoner, a spokesman for First Energy, which acquired Potomac Edison in 2011.

Pepco says it has stepped up spending to improve reliability by $910 million across five years.

Pepco had massive, sustained outages in 2010 and 2011 that left thousands of customers in Montgomery and Prince George's counties angry and waiting days or more than a week for service. Its performance led to the push for the PSC to set objective standards to make utilities accountable.

Pepco announced the five-year plan after the PSC opened an investigation into its performance in August 2010. Late last year, the PSC fined the utility $1 million after finding Pepco had been “imprudent” in not trimming enough to keep trees and limbs from hitting power lines and interrupting service.

Minimum standards also are set for inspecting utility poles (every 10 years), overhead primary lines from substations (every two years), transformers (every five years) and substations (every two months).

In August, each utility will have to file with the PSC a copy of its program for operating and maintaining its distribution equipment, a copy of its plan and procedures for responding to major outages and a copy of its tree-trimming plan.

Utilities also are required to file plans to correct problems if they fail to meet a variety of new minimum standards, including not just the length and frequency of outages, but the time it takes to respond to downed wires that pose safety hazards, the time it takes to improve reliability on power lines with the highest failure rates and the time it takes to answer customer calls.

The new standards "really put the focus on asset management — the evaluation, tracking and inventory of the system infrastructure," said Thomas Dennison, spokesman for Southern Maryland Electric Cooperative.

With fewer than 500 employees, SMECO was able to realign staff to cover much of the work, but will have to hire some additional personnel, particularly in the call center, Dennison said.

But "SMECO entered into the process as a very well-performing utility," he said.

SMECO customers had the shortest outages and experienced outages less often than all but one of the six largest Maryland utilities, according to data from 2005 through 2009.

Although the standards have benefits, Dennison said, "they come with real quantifiable costs, that in a not-for-profit utility [cooperative such as SMECO] can only come through ratepayers."